1. Field of the Invention
The present invention relates generally to devices for the internal fixation of the spine particularly within the fields of orthopedics and/or neurosurgery such as spinal implants for holding vertebral bones fixed relative to one another and, more particularly, to static bone fixation implants for use in spinal surgical procedures for stabilizing the relative motion of, temporarily or permanently immobilizing, bones of the spine.
2. Background Information
Spine plates have been used for more than 20 years to increase spine stability following single and multi-level spine surgery. Plates implanted during surgery for reasons such as disease, trauma, defect, accident or the like, are used to stabilize one or more spinal vertebrae. Stabilization leads to a proper healing or a desired outcome. The plate is mounted to one or more vertebrae during the surgery. Typically, bone screws are used to mount the plate to the one or more vertebrae. It is important during the mounting process that the plate be properly aligned on the vertebrae for receipt of the mounting screws.
In some instances, it is desirous to cause the fusion of two adjacent vertebrae. If this is the case, the surgeon makes an incision to reach the spine. Tissues and muscles are retracted (spread apart) to reveal the proper level in the spine. The cartilaginous material or disc between the two vertebrae is removed and the bone surface abraded to encourage a bleeding surface. Blood from the bleeding surfaces is desired in order for the bones to fuse. The space between the adjacent vertebrae is filled with bone graft. A plate is then screwed into the superior (top) and inferior (bottom) vertebrae. This stabilizes the spine to facilitate fusion and healing.
In all cases, the spine plates must be fastened to the vertebrae. This is accomplished by bone screws. The bone screws are received in bores of the spine plate and hold the spine plate to the vertebra. In order to prevent anti-rotation or “backing out” of the bone screw once it has been rotated into the bone (vertebra), caps or prong structures are placed into drive sockets in the heads of the bone screws. This detrimentally adds an extra component to the plate assembly or construct. It would be desirable to provide a spine plate and/or spine plate assembly that eliminates this extra component.
Moreover, bone screw bores of current spine plates do not have the configuration or geometry to allow angulation of bone screws as appropriate or to prohibit angulation of bone screws as appropriate while providing a positive retention of the bone screw by the plate alone. It would be desirable to provide a spine plate and/or spine plate assembly having bone screw bores that are configured to provide for angulation of a bone screw and/or the prohibition of angulation of a bone screw as appropriate while providing a positive retention of the bone screw by the plate alone.
Other objects will become apparent from the following.